1. Field of the Invention
The present invention relates to an injector head for medical use, and more particularly relates to improvement of the structure of the injector head for medical use.
2. Description of the Background Art
Various apparatuses for testing the function of the human body have been developed recently. One example is a circulatory organ x-ray diagnostic apparatus for diagnosing the function of the circulatory organ of the human body. With reference to FIG. 2, a general description of the circulatory organ x-ray diagnostic apparatus will be given.
A circulatory organ x-ray diagnostic apparatus 100 is provided with a rail 103 attached to a ceiling 101. An x-ray apparatus 102 which is movable freely in X and Y directions is attached to rail 103. A catheter table 104 for laying a patient 106 at a prescribed position is arranged at a prescribed position.
A side of catheter table 104 has a guide rail 108. Guide rail 108 has an equipment attached for performing the procedure necessary for the x-ray diagnosis for patient 106. In FIG. 2, for example, a support unit 200 is mounted on guide rail 108, and an injector head for medical use 112 for injecting contrast medium into patient 106 is attached to support unit 200 via a stanchion 114. By moving support unit 200 along guide rail 108 medical injector head 112 can be positioned at patient 106, and interference with any other apparatus can be avoided.
A syringe 10 into which the contrast medium is injected is attached to medical injector head 112. When the contrast medium is injected into patient 106 using medical injector head 112, medical injector head 112 is inclined downward such that an injection unit 10a of syringe 10 faces downward. Even if air bubbles enter syringe 10, injection of air bubbles into patient 106 can be prevented by arranging injection unit 10a of syringe 10 to face downward in order to collect the air bubbles in the rear end portion of syringe 10 as shown in FIG. 3A.
On the other hand, when the air bubbles entering syringe 10 are to be discharged or the contrast medium is to be sucked into syringe 10, medical injector head 112 is inclined upward such that injection unit 10a of syringe 10 faces upward as shown in FIG. 3B. The air bubbles entering syringe 10 at the time of the sucking can easily be discharged from injection unit 10a of syringe 10 to the outside after the injection.
Next with reference to FIG. 4, the mechanism of injector head for medical use 112 is described.
Medical injector head 112 includes a plunger 21 joined to a piston 20 provided in syringe 10. Rotation of a motor 30 is propagated to a ball screw 22, and plunger 21 can be moved forward and backward by ball screw 22.
Motor 30 is provided with a potentiometer 23 for sensing a position of plunger 21. A plunger position signal S3 output from potentiometer 23 is supplied to a body control unit 200.
A motor drive voltage S2 is output from body control unit 200 to motor 30. When an amount of injection of the contrast medium into a patient is input to a control panel 150, a corresponding signal is output from control panel 150 to body control unit 200, and motor drive voltage S2 is output from body control unit 200 to motor 30. At this time, plunger position signal S3 is supplied from potentiometer 23 to body control unit 200 as a feedback signal. Accordingly, the position of plunger 21 can be controlled correctly, and the contrast medium can be injected highly accurately into the patient.
Injector head for medical use 112 is further provided with an switch 50 for advancing and retracting plunger 21 by manual operation, as well as a manual knob 112b (see FIG. 3A). A variable forward/reverse switch is utilized as switch 50 which is capable of varying the speed in forward and backward movements by changing the position on the switch to be pressed.
A signal from switch 50 is output to a switch circuit 40 and a switch signal S100 is supplied to body control unit 200. Motor drive voltage S2 is thereafter output from body control unit 200 to motor 30.
When the contrast medium is injected into patient 106 by inclining medical injector head 112 downward as shown in FIG. 3A, sucking is performed slowly in order to check if a catheter is inserted into the blood vessel of patient 106. If the blood rises into the catheter, it means that the catheter has been surely inserted into the blood vessel.
In this case, if the contrast medium is sucked at higher speed, the blood flows backward into the catheter and enters syringe 10. An operator of injector head 112 such as a nurse or a medical technologist needs to operate switch 50 or manual knob 112b such that the piston is moved very carefully and slowly.